[{"sentiment": "Extends", "sentence": "Our experimental design with professional bilingual translators follows our previous work Green et al. ( 2013a ) comparing scratch translation to post-edit .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "Following our previous work on stance classification ( Hasan and Ng , 2013c ) , we employ three types of features computed based on the frame-semantic parse of each sentence in a post obtained from SEMAFOR ( Das et al. , 2010 ) .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "In our previous work ( Zhang and Chai , 2009 ) , we started an initial investigation on conversation entailment .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "SWIZZLE is a multilingual enhancement of COCKTAIL ( Harabagiu and Maiorano , 1999 ) , a coreference resolution system that operates on a mixture of heuristics that combine semantic and textual cohesive information ' .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "To address this limitation , our previous work ( Zhang and Chai , 2009 ) has initiated an investigation on the problem of conversation entailment .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "The features can be easily obtained by modifying the TAT extraction algorithm described in ( Liu et al. , 2006 ) .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "In previous work ( Bachenko et al. 1986 ) , we described an experimental text-to-speech system that determined prosodic phrasing for the Olive -- Liberman synthesizer ( Olive and Liberman 1985 ) .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "Expanding on a suggestion of Michiels ( 1982 ) , we classify verbs as Subject Equi , Object Equi , Subject Raising or Object Raising for each sense which has a predicate complement code associated with it .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "8 It is based on the dataset of Pang and Lee ( 2004 ) ,9 which consists of 1000 positive and 1000 negative movie reviews , tokenized and divided into 10 folds ( F0 -- F9 ) .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "The diagnoser , based on Dzikovska et al. ( 2008b ) , outputs a diagnosis which consists of lists of correct , contradictory and non-mentioned objects and relations from the student 's answer .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "Note that although our feature set was drawn primarily from our prior uncertainty detection experiments ( Forbes-Riley and Litman , 2011a ; Drummond and Litman , 2011 ) , we have also experimented with other features , including state-of-theart acoustic-prosodic features used in the last Interspeech Challenges ( Schuller et al. , 2010 ; Schuller et al. , 2009b ) and made freely available in the openSMILE Toolkit ( Florian et al. , 2010 ) .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "The same annotation scheme as in our previous work on anger detection has been applied , see e.g. ( Schmitt et al. , 2009 ) .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "The framework represents a generalization of several predecessor NLG systems based on Meaning-Text Theory : FoG ( Kittredge and Polguere , 1991 ) , LFS ( Iordanskaja et al. , 1992 ) , and JOYCE ( Rambow and Korelsky , 1992 ) .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "( Details of how the average-expert model performs can be found in our prior work ( Xiong and Litman , 2011 ) . )", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "Experiments ( Section 5 ) show that forestbased extraction improves BLEU score by over 1 point on a state-of-the-art tree-to-string system ( Liu et al. , 2006 ; Mi et al. , 2008 ) , which is also 0.5 points better than ( and twice as fast as ) extracting on 30-best parses .", "aspect": "aclintent"}, {"sentiment": "Extends", "sentence": "Andrews et al. ( 2009 ) furthered this work by showing that a bimodal topic model , consisting of both text and feature norms , outperformed models using only one modality on the prediction of association norms , word substitution errors , and semantic interference tasks .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "Perhaps some variation of multi-level bulleted lists , appropriately integrated with interface elements for expanding and hiding items , might provide physicians a better overview of the information landscape ; see , for example , Demner-Fushman and Lin ( 2006 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "For projective parsing , it is significantly faster than exact dynamic programming , at the cost of small amounts of search error , We are interested in extending these ideas to phrase-structure and lattice parsing , and in trying other higher-order features , such as those used in parse reranking ( Charniak and Johnson , 2005 ; Huang , 2008 ) and history-based parsing ( Nivre and McDonald , 2008 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "The analysis of the data we have collected indicates that student satisfaction may be affected if the system rephrases student answers using different words ( for example , using better terminology ) but does n't explicitly explain the reason why different terminology is needed ( Dzikovska et al. , 2010 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "Regarding future work , there are many research line that may be followed : i ) Capturing more features by employing external knowledge such as ontological , lexical resource or WordNet-based features ( Basili et al. , 2005a ; Basili et al. , 2005b ; Bloehdorn et al. , 2006 ; Bloehdorn and Moschitti , 2007 ) or shallow semantic trees , ( Giuglea and Moschitti , 2004 ; Giuglea and Moschitti , 2006 ; Moschitti and Bejan , 2004 ; Moschitti et al. , 2007 ; Moschitti , 2008 ; Moschitti et al. , 2008 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "In the future , we hope to evaluate the automatic annotations and extracted lexicon against Propbank ( Kingsbury and Palmer 2002 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "We perceive that these results can be extended to other language models that properly embed bilexical context-free grammars , as for instance the more general history-based models used in ( Ratnaparkhi , 1997 ) and ( Chelba and Jelinek , 1998 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "At present , the system uses a heuristic matching algorithm to classify relations into the appropriate category , though in the future we may consider a classifier similar to Nielsen et al. ( 2008 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "Another interesting extension is to broaden the definition of a `` word '' to include multi-word lexical units ( Smadja , 1992 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "As ( Daelemans et al. , 1999 ) show , lexical information improves on NP and VP chunking as well .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "Better results would be expected by combining the PCFG-LA parser with discriminative reranking approaches ( Charniak and Johnson , 2005 ; Huang , 2008 ) for self training .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "For example , it would be helpful to consider strong correspondence between certain English and Chinese words , as in ( Wu , 1994 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "To address this problem , we are currently working on developing a metagrammar in the sense of ( Candito , 1999 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "In particular , ( Gross , 1989 ) lists the converses of some 3 500 predicative nouns .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "There have been several efforts aimed at developing a domain-independent method for generating responses from a frame representation of user requests ( Bobrow et al. , 1977 ; Chu-Carroll , 1999 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "We could also introduce new variables , e.g. , nonterminal refinements ( Matsuzaki et al. , 2005 ) , or secondary links Mid ( not constrained by TREE/PTREE ) that augment the parse with representations of control , binding , etc. ( Sleator and Temperley , 1993 ; Buch-Kromann , 2006 ) .", "aspect": "aclintent"}, {"sentiment": "Future", "sentence": "Such a component would serve as the first stage of a clinical question answering system ( Demner-Fushman and Lin , 2005 ) or summarization system ( McKeown et al. , 2003 ) .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "Agreement between two annotation sets is calculated here in terms of Cohen 's kappa ( Cohen , 1960 ) 1 and corrected kappa ( Brennan and Prediger , 1981 ) 2 .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "We use the non-projective k-best MST algorithm to generate k-best lists ( Hall , 2007 ) , where k = 8 for the experiments in this paper .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "Using the GHKM algorithm ( Galley et al. 2004 ) , we can get two different STSG derivations from the two U-trees based on the fixed word alignment .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "As in ( Lee et al. , 2003 ) , we used unsupervised training data which is automatically segmented to discover previously unseen stems .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "Accuracy is not the best measure to assess segmentation quality , therefore we also conducted experiments using the WindowDiff measure as proposed by Pevzner and Hearst ( 2002 ) .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "SNoW ( Carleson et al. , 1999 ; Roth , 1998 ) is a multi-class classifier that is specifically tailored for learning in domains in which the potential number of information sources ( features ) taking part in decisions is very large , of which NLP is a principal example .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "We follow Stymne and Cancedda ( 2011 ) , for compound merging .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "Venables and Ripley ( 1994 ) describe an efficient algorithm ( of linear complexity in the number of training sentences ) for computing the LDA transform matrix , which entails computing the withinand between-covariance matrices of the classes , and using Singular Value Decomposition ( SVD ) to compute the eigenvectors of the new space .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "The elimination of redundant nondeterminism is based on Unfold/Fold transformation techniques ( Tamaki and Sato 1984 ) .29 The unfolding transformation is also referred to as partial execution , for example , by Pereira and Shieber ( 1987 ) .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "One , the VOYAGER domain ( Zue et al. 1990 ) , answers questions about places of interest in an urban area , in our case , the vicinity of MIT and Harvard University .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "Finally , we experiment with a method for combining phrase tables proposed in ( Nakov and Ng , 2009 ; Nakov and Ng , 2012 ) .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "results are based on a corpus of movie subtitles ( Tiedemann 2007 ) , and are consequently shorter sentences , whereas the En \u00e2\u0086\u0092 Es results are based on a corpus of parliamentary proceedings ( Koehn 2005 ) .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "Developed Systems Our developed system is built on the work by Chang et al. ( 2013 ) , using Constrained Latent Left-Linking Model ( CL3M ) as our mention-pair coreference model in the joint framework10 .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "We use an in-house statistical tagger ( based on ( Church , 1988 ) ) to tag the text in which the unknown word occurs .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "We further add rules for combining with punctuation to the left and right and allow for the merge rule X \u00e2\u0086\u0092 X X of Clark and Curran ( 2007 ) .", "aspect": "aclintent"}, {"sentiment": "Uses", "sentence": "Therefore , we preprocess Ontonote-5 .0 to derive mention heads using Collins head rules ( Collins , 1999 ) with gold constituency parsing information and gold named entity information .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "Our method resorts to some translation examples , which is similar as example-based translation or translation memory ( Watanabe and Sumita , 2003 ; He et al. , 2010 ; Ma et al. , 2011 ) .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "Our most accurate single grammar achieves an F score of 91.6 on the WSJ test set , rivaling discriminative reranking approaches ( Charniak and Johnson , 2005 ) and products of latent variable grammars ( Petrov , 2010 ) , despite being a single generative PCFG .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "This is the approach taken by IBM Models 4 + ( Brown et al. 1993b ; Och and Ney 2003 ) , and more recently by the LEAF model ( Fraser and Marcu 2007 ) .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "coreference performance on perfect mentions ( e.g. , Incorporate the two knowledge sources in a Luo et al. ( 2004 ) ) ; and for those that do report percoreference resolver .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "The automation of help-desk responses has been previously tackled using mainly knowledge-intensive paradigms , such as expert systems ( Barr and Tessler 1995 ) and case-based reasoning ( Watson 1997 ) .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "The best performance on the WSJ corpus was achieved by a combination of the SATZ system ( Palmer and Hearst 1997 ) with the Alembic system ( Aberdeen et al. 1995 ) : a 0.5 % error rate .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "Numerous previous pseudodisambiguation evaluations only include arguments that occur between 30 and 3000 times ( Erk , 2007 ; Keller and Lapata , 2003 ; Rooth et al. , 1999 ) .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "The standard way to handle this problem is to handcraft a finite set of features which provides a sufficient summary of the unbounded history ( Ratnaparkhi , 1999 ; Collins , 1999 ; Charniak , 2000 ) .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "This revalidates the observation of Nguyen et al. ( 2009 ) that phrase structure representations and dependency representations add complimentary value to the learning task .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "However , most strategies are based on `` internal '' or `` external methods '' ( Grabar and Zweigenbaum , 2002 ) , i.e. methods that rely on the form of terms or on the information gathered from contexts .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "Collins 1996 , Charniak 1997 , Collins 1999 and Charniak 2000 ) .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "This seems to provide additional evidence of Bruni et al. ( 2012b ) 's suggestion that something like a distributional hypothesis of images is plausible .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "HOLMES is given the following set of six domainindependent rules , which are similar to the upward monotone rules introduced by ( MacCartney and Manning , 2007 ) .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "The coreference system system is similar to the Bell tree algorithm as described by ( Luo et al. , 2004 ) .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "Indeed , such rich semantic links can be used to extend indices or reformulate queries ( similar to the work by Voorhees ( 1994 ) with WoRDNET relations ) .", "aspect": "aclintent"}, {"sentiment": "CompareOrContrast", "sentence": "Although evaluated on different data sets , this result is consistent with results from previous work ( Gatt and Belz , 2008 ; Gatt et al. , 2009 ) .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "Recently , several alternative , often quite sophisticated approaches to collective classification have been proposed ( Neville and Jensen , 2000 ; Lafferty et al. , 2001 ; Getoor et al. , 2002 ; Taskar et al. , 2002 ; Taskar et al. , 2003 ; Taskar et al. , 2004 ; McCallum and Wellner , 2004 ) .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "A logic that provides the formal architecture required by Pollard and Sag ( 1994 ) was defined by King ( 1989 , 1994 ) .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "In other methods , lexical resources are specifically tailored to meet the requirements of the domain ( Rosario and Hearst , 2001 ) or the system ( Gomez , 1998 ) .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "Barzilay and McKeown ( 2001 ) also note that the applicability of paraphrases is strongly influenced by context .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "Other work on modeling the meanings of verbs using video recognition has also begun showing great promise ( Mathe et al. , 2008 ; Regneri et al. , 2013 ) .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "This paper describes an approach for sharing resources in various grammar formalisms such as Feature-Based Lexicalized Tree Adjoining Grammar ( FB-LTAG1 ) ( Vijay-Shanker , 1987 ; Vijay-Shanker and Joshi , 1988 ) and Head-Driven Phrase Structure Grammar ( HPSG ) ( Pollard and Sag , 1994 ) by a method of grammar conversion .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "Liu et al. ( 2005 ) , Meral et al. ( 2007 ) , Murphy ( 2001 ) , Murphy and Vogel ( 2007 ) and Topkara et al. ( 2006a ) all belong to the syntactic transformation category .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "The extraction procedure consists of three steps : First , the bracketing of the trees in the Penn Treebank is corrected and extended based on the approaches of Magerman ( 1994 ) and Collins ( 1997 ) .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "The use of the web as a corpus for teaching and research on language has been proposed a number of times ( Kilgarriff , 2001 ; Robb , 2003 ; Rundell , 2000 ; Fletcher , 2001 , 2004b ) and received a special issue of the journal Computational Linguistics ( Kilgarriff and Grefenstette , 2003 ) .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "The exact form of M ( Si ) need not be discussed at this point ; it could be a conceptual dependence graph ( Schank and Abelson 1977 ) , a deep parse of Si , or some other representation .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "Xue and Palmer ( 2004 ) did very encouraging work on the feature calibration of semantic role labeling .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "An off-the-shelf speech recognition device , a Nippon Electric Corporation DP-200 , was added to an existing natural language processing system , the Natural Language Computer ( NLC ) ( Ballard 1979 , Biermann and Ballard 1980 ) .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "There is a general consensus among theoretical linguists that the proper representation of verbal argument structure is event structure -- representations grounded in a theory of events that decompose semantic roles in terms of primitive predicates representing concepts such as causality and inchoativity ( Dowty , 1979 ; Jackendoff , 1983 ; Pustejovsky , 1991b ; Rappaport Hovav and Levin , 1998 ) .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "Some works abstract perception via the usage of symbolic logic representations ( Chen et al. , 2010 ; Chen and Mooney , 2011 ; Matuszek et al. , 2012 ; Artzi and Zettlemoyer , 2013 ) , while others choose to employ concepts elicited from psycholinguistic and cognition studies .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "For example , the forward-backward algorithm ( Baum , 1972 ) trains only Hidden Markov Models , while ( Ristad and Yianilos , 1996 ) trains only stochastic edit distance .", "aspect": "aclintent"}, {"sentiment": "Background", "sentence": "Furthermore , the availability of rich ontological resources , in the form of the Unified Medical Language System ( UMLS ) ( Lindberg et al. , 1993 ) , and the availability of software that leverages this knowledge -- MetaMap ( Aronson , 2001 ) for concept identification and SemRep ( Rindflesch and Fiszman , 2003 ) for relation extraction -- provide a foundation for studying the role of semantics in various tasks .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "porating these two KSs into our resolver : they can Following Soon et al. ( 2001 ) , we select as the aneach be represented as a constraint or as a feature , tecedent of each NP , NPS , the closest preceding NP and they can be applied to the resolver in isolation that is classified as coreferent with NPS .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "But their importance has grown far beyond machine translation : for instance , transferring annotations between languages ( Yarowsky and Ngai 2001 ; Hwa et al. 2005 ; Ganchev , Gillenwater , and Taskar 2009 ) ; discovery of paraphrases ( Bannard and Callison-Burch 2005 ) ; and joint unsupervised POS and parser induction across languages ( Snyder and Barzilay 2008 ) .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "As noted above , it is well documented ( Roland and Jurafsky 1998 ) that subcategorization frames ( and their frequencies ) vary across domains .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "Our HDP extension is also inspired from the Bayesian model proposed by Haghighi and Klein ( 2007 ) .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "Specifically , we examine the strength of association between the verb and the noun constituent of a combination ( the target expression or its lexical variants ) as an indirect cue to its idiomaticity , an approach inspired by Lin ( 1999 ) .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "As suggested in Rapp & Zock ( 2010 ) this can be done by looking up the ranks of each of the four given words ( i.e. the words occurring in a particular word equation ) within the association vector of a translation candidate , and by multiplying these ranks .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "Each component will return a confidence measure of the reliability of its prediction , c.f. ( Elworthy , 1998 ) .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "As shown in Meurers ( 1994 ) this is a well-motivated convention since it avoids splitting up lexical rules to transfer the specifications that must be preserved for different lexical entries .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "This strategy is certainly the right one to start out with , since anaphora is always the more typical direction of reference in English prose ( Halliday and Hasan 1976 , p. 329 ) .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "Dalrymple ( 2001 ) argues that there are cases , albeit exceptional ones , in which constraints on syntactic category are an issue in subcategorization .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "The work is carried out in order to assist terminographers in the enrichment of a dictionary on computing that includes collocational information ( L'Homme , 2004 ) .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "But their importance has grown far beyond machine translation : for instance , transferring annotations between languages ( Yarowsky and Ngai 2001 ; Hwa et al. 2005 ; Ganchev , Gillenwater , and Taskar 2009 ) ; discovery of paraphrases ( Bannard and Callison-Burch 2005 ) ; and joint unsupervised POS and parser induction across languages ( Snyder and Barzilay 2008 ) .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "Problems such as these have motivated research on more abstract , dependencybased parser evaluation ( e.g. , Lin 1995 ; Carroll , Briscoe , and Sanfilippo 1998 ; Carroll et al. 2002 ; Clark and Hockenmaier 2002 ; King et al. 2003 ; Preiss 2003 ; Kaplan et al. 2004 ; Miyao and Tsujii 2004 ) .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "Differently , Cohn and Blunsom ( 2009 ) designed a sampler to infer an STSG by fixing the tree structure and exploring the space of alignment .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "But their importance has grown far beyond machine translation : for instance , transferring annotations between languages ( Yarowsky and Ngai 2001 ; Hwa et al. 2005 ; Ganchev , Gillenwater , and Taskar 2009 ) ; discovery of paraphrases ( Bannard and Callison-Burch 2005 ) ; and joint unsupervised POS and parser induction across languages ( Snyder and Barzilay 2008 ) .", "aspect": "aclintent"}, {"sentiment": "Motivation", "sentence": "TF is given by TFD , t , and it denotes frequency of term t in document D. IDF is given by IDFt = log ( N/dft ) , where N is the number of documents in the collection , and dft is the number of documents containing the term t. ( Salton and Yang , 1973 ) proposed the combination of TF and IDF as weighting schemes , and it has been shown that their product gave better performance .", "aspect": "aclintent"}]